I've asked this on the David Brown Collector's Club forum out of the UK and haven't gotten an answer,so I'll take a stab at it here. Is there an engine serial number or some date code that would tell when an 850 or Oliver 500 was built? I have Oliver 500 serial number 3. From articles I've read,DB built two and sent them to Albany Georgia for testing and demonstration in December of 1959. When they made the deal to sell them as Olivers,one stipulation was that they had to have an Oliver serial tag. This one doesn't have one. It just has a small brass tag that says Made in England where the serial tag should be,so I'm just trying to figure out if it was one of those shipped in 59.